scholarly journals Dynamic solvatochromism in solvent mixtures

2001 ◽  
Vol 73 (3) ◽  
pp. 405-409 ◽  
Author(s):  
Diana E. Wetzler ◽  
Carlos Chesta ◽  
Roberto Fernández-Prini ◽  
Pedro F. Aramendía
Keyword(s):  
Excited State ◽  
Ground State ◽  
Emission Spectroscopy ◽  
Characteristic Time ◽  
Polar Solvent ◽  
Emission Spectra ◽  
Spectral Shift ◽  
Solvent Mixtures ◽  
Time Resolved ◽  
Different Temperatures

Solvatochromism and thermochromism of 4-aminophthalimide and 4-amino-N-methylphthalimide were studied by absorption and steady-state and time-resolved emission spectroscopy in solvent mixtures of toluene­ethanol and toluene­acetonitrile at different temperatures. Emission spectra shift to the red upon addition of a polar solvent (PS) to toluene. Solvent mixtures show a much greater thermochromic shift to the blue in emission than the neat solvents. This is explained by the decrease in temperature of the exothermic association of the polar solvent to the excited state. Emission spectra are time dependent in solvent mixtures in the ns timescale. The time evolution of this emission is interpreted on the basis of the different solvation of the ground state and the emitting excited state. Stern­Volmer plots are obtained for the dependence of the spectral-shift characteristic time with [PS].

Experimental evidence for the influence of the excitation wavelength on the value of the equilibrium constant as determined by Time-Resolved Emission Spectroscopy (TRES)

2006 ◽  
Vol 94 (5) ◽  
Author(s):  
Isabelle Billard ◽  
Gilles Montavon ◽  
Sandrine Markai ◽  
Catherine Galindo
Keyword(s):  
Emission Spectroscopy ◽  
Emission Spectra ◽  
Chemical System ◽  
Excitation Wavelength ◽  
Physical Parameters ◽  
Antenna Effect ◽  
Europium Complexes ◽  
Time Resolved ◽  
Photochemical Process ◽  
Direct Excitation

SummaryIn the case of a rapid photochemical process, a new theoretical result relating time-resolved emission spectroscopy data to three physical parameters of the chemical system has been recently proposed. This previous work, based on a simulation study, is experimentally evidenced in the present paper, using europium/acetate as a model system. The comparison of the emission spectra obtained upon direct excitation of europium (394 nm) and by use of the “antenna effect” (266 nm) evidences the occurring of a back-dissociation of excited europium complexes to form solvated excited free europium ions.

Spectral and Photoprototropic Characteristics of 4-Aminobiphenyl in β-Cyclodextrin

2004 ◽  
Vol 69 (4) ◽  
pp. 748-758 ◽  
Author(s):  
Israel V. Muthu Vijayan Enoch ◽  
Meenakshisundaram Swaminathan
Keyword(s):  
Excited State ◽  
Steady State ◽  
Fluorescence Spectroscopy ◽  
Inclusion Complex ◽  
Ground State ◽  
Time Resolved Fluorescence ◽  
Neutral Form ◽  
Time Resolved ◽  
Time Resolved Spectroscopy

The photophysical and photoprototropic behaviour of 4-aminobiphenyl (4ABP) in aqueous β-cyclodextrin (β-CDx) solution has been investigated using steady-state and time-resolved fluorescence spectroscopy. Fluorescence of the neutral form of 4ABP is enhanced due to the formation of a 1:1 complex with β-CDx. The formation of this complex has been confirmed by time-resolved spectroscopy. In the presence of β-CDx, no change was observed in the ground state pKa value but the excited state pKa value changed. Based on its photophysical and photoprototropic characteristics in β-CDx, the structure of the 1:1 inclusion complex is proposed.

Monitoring the Formation and Decay of Transient Photosensitized Intermediates Using Pump-Probe UV Resonance Raman Spectroscopy. I: Self-Modeling Curve Resolution

2003 ◽  
Vol 57 (4) ◽  
pp. 439-447 ◽  
Author(s):  
James A. Kleimeyer ◽  
Joel M. Harris
Keyword(s):  
Factor Analysis ◽  
Excited State ◽  
Ground State ◽  
Pure Component ◽  
Triplet States ◽  
Time Resolved ◽  
Pump Probe ◽  
Excited Triplet ◽  
Curve Resolution ◽  
Excited Triplet States

Resolution of transient excited-state Raman scattering from ground-state and solvent bands is a challenging spectroscopic measurement since excited-state spectral features are often of low intensity, overlapping the dominant ground-state and solvent bands. The Raman spectra of these intermediates can be resolved, however, by acquiring time-resolved data and using multidimensional data analysis methods. In the absence of a physical model describing the kinetic behavior of a reaction, resolution of the pure-component spectra from these data can be accomplished using self-modeling curve resolution, a factor analysis technique that relies on the correlation in the data along a changing composition dimension to resolve the component spectra. A two-laser UV pump-probe resonance-enhanced Raman instrument was utilized to monitor the kinetics of amine quenching of excited-triplet states of benzophenone. The formation and decay of transient intermediates were monitored over time, from 15 ns to 100 μs. Factor analysis of the time-resolved spectral data identified three significant components in the data. The time-resolved intensities at each Raman wavenumber shift were projected onto the three significant eigenvectors, and least-squares criteria were developed to find the common plane in the space of the eigenvectors that includes the observed data. Within that plane, the three pure-component spectra were resolved using geometric criteria of convex hull analysis. The resolved spectra were found to arise from benzophenone excited-triplet states, diphenylketyl radicals, and the solvent and ground-state benzophenone.

scholarly journals Estimating the Ground and Excited State Dipole Moments of Levofloxacin and Norfloxacin Drugs Using Solvatochromic Effects and Computational Work

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Kinfe Woldegiorges ◽  
Abebe Belay ◽  
Alemu Kebede ◽  
Tamirat Abebe
Keyword(s):  
Excited State ◽  
Ground State ◽  
Dipole Moments ◽  
Bacterial Species ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Electron Charge Density ◽  
Nonpolar Solvents ◽  
Computational Work ◽  
Excited State Dipole Moments

Levofloxacin (LVF) and norfloxacin (NRF) are a group of fluoroquinolone antibiotics, broad spectrum used to treat various infections caused by many bacterial species. The drugs contain functional groups which control the type and degree of interaction with different solvents. In this research, the ground and excited state dipole moments of LVF and NRF drugs were estimated using solvatochromic effects and computational work. The dipole moments were estimated from absorption and emission spectra in polar and nonpolar solvents using Bakhshiev’s, Kawski–Chamma–Viallet, Lippert–Mataga, and Reichardt models. The results indicated the emission spectra are more strongly affected by solvent polarity than the absorption spectra. The calculated excited state dipole moment is larger than that of the ground state, indicating that the probe compounds are significantly more polarized in the excited state than in the ground state. From computational work, the HOMO-LUMO energy band gap, the dipole moments, electron charge density distribution, and oscillator strength were determined using the semiempirical MP6 method, DFT-B3LYP-6-31G, and DFT-B3LYP-3-21G employing Gaussian 09 software. In general, larger dipole moments were obtained by computation rather than from experiments due to the absence of solvent effects.

Excited state dynamics and time-resolved photoelectron spectroscopy of para-xylylene

2018 ◽  
Vol 212 ◽  
pp. 83-100 ◽  
Author(s):  
Kevin Issler ◽  
Anja Röder ◽  
Florian Hirsch ◽  
Lionel Poisson ◽  
Ingo Fischer ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Time Scale ◽  
Time Resolved ◽  
Surface Hopping ◽  
Excited State Dynamics ◽  
Ultraviolet Excitation ◽  
Step Mechanism

We investigated the excited-state dynamics of para-xylylene using a combination of field-induced surface hopping simulations and time-resolved photoionisation experiments. Ultraviolet excitation is followed by nonadiabatic relaxation to the ground state in a two-step mechanism on the sub-ps time scale.

scholarly journals Solvent effect on the absorption and emission spectra of carbon dots: evaluation of ground and excited state dipole moment

BMC Chemistry ◽  
2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Parisa Mohammad-Jafarieh ◽  
Abolfazl Akbarzadeh ◽  
Rahman Salamat-Ahangari ◽  
Mohammad Pourhassan-Moghaddam ◽  
Kazem Jamshidi-Ghaleh
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Ground State ◽  
Carbon Dots ◽  
Dipole Moments ◽  
Emission Spectra ◽  
Aprotic Solvents ◽  
One Step ◽  
The Difference ◽  
Excited State Dipole Moment

Abstract Background Carbon dots (C-dots) are photoluminescent nanoparticles with less than 10 nm in size. Today, many studies are performed to exploit the photoluminescence (PL) property of carbon dots, and our focus in this study is to estimate the dipole moment of carbon dots. For reaching our aims, C-dots were synthesized and dissolved in the different solvents. Results Carbon dots with intense photoluminescence properties have been synthesized by a one-step hydrothermal method from a carbon bio-source. In this research, we report on the effect of aprotic solvents on absorption and fluorescence spectra and dipole moments of C-dots dispersed in a range of many aprotic solvents with various polarity and dielectric constant at room temperature. The change in the value of dipole moment was estimated by using the Stokes shifts. The difference between the dipole moment of the excited state and the ground state was shown using an extended form of Lippert equations by Kawski and co-workers. Conclusions The values found for μg = 1.077 D, and μe = 3.157 D, as well as the change in the dipole moments. The results showed that the dipole moment of the excited state is more than the ground state, indicating a high density and redistribution of electrons in the excited state. Finally, the quantum yield of C-dots in the eclectic aprotic solvents was communicated and discussed.

Sign in / Sign up

Export Citation Format

Share Document